Women who do not need pain relief during childbirth may be carriers of a key genetic variant that acts a natural epidural, say scientists at the University of Cambridge.
Nature’s epidural: Genetic variant may explain why some women don’t need pain relief during childbirth
In a study published in the journal Cell Reports, the researchers explain how the variant limits the ability of nerve cells to send pain signals to the brain.
Childbirth is widely recognised as a painful experience. However, every woman’s experience of labour and birth is unique, and the level of discomfort and pain experienced during labour varies substantially between women.
A collaboration between clinicians and scientists based at Addenbrooke’s Hospital, part of Cambridge University Hospitals NHS Foundation Trust (CUH), and the University of Cambridge sought to investigate why some mothers report less pain during labour.
A group of women was recruited and characterised by the team led by Dr Michael Lee from the University’s Division of Anaesthesia. All the women had carried their first-born to full term and did not request any pain relief during an uncomplicated vaginal delivery. Dr Lee and colleagues carried out a number of tests on the women, including applying heat and pressure to their arms and getting them to plunge their hands into icy water.
Compared to a control group of women that experienced similar births, but were given pain relief, the test group showed higher pain thresholds for heat, cold and mechanical pressure, consistent with them not requesting pain relief during childbirth. The researchers found no differences in the emotional and cognitive abilities of either group, suggesting an intrinsic difference in their ability to detect pain.
“It is unusual for women to not request gas and air, or epidural for pain relief during labour, particularly when delivering for the first time,” said Dr Lee, joint first author. “When we tested these women, it was clear their pain threshold was generally much higher than it was for other women.”
Next, senior co-author, Professor Geoff Woods, and his colleagues at the Cambridge Institute for Medical Research sequenced the genetic code of both groups of women and found that those in the test group had a higher-than-expected prevalence of a rare variant of the gene KCNG4. It’s estimated that one approximately 1 in 100 women carry this variant.
Image: Mother and newborn baby
Reproduced courtesy of the University of Cambridge
The University of Cambridge is acknowledged as one of the world's leading higher education and research institutions. The University was instrumental in the formation of the Cambridge Network and its Vice- Chancellor, Professor Stephen Toope, is also the President of the Cambridge Network.